Many places say that you need to cover wires when plastering over them:
In a zone or not I would still steel cap the cables even if they were only TV Aerial cables.
IMO PVC capping is safer, as long as it's in the zone, as there is no chance of it becoming live.
If clipping direct to a wall then reasonable protection is needed from the plasterers trowel.
There is diynot.com/forums:
Capping of any sort is not required by the regs
and finally this
Nothing wrong with plastering directly over the cables though. As said, the capping was more to prevent damage during plastering and although there is no direct mention if this in the regs, it was the intended purpose.
So some say that it is needed, some say it is worthless... Who is right? Do I need to cap the wires?